feat: add environment configuration and SQLite migration support

src/config.ts

@@ -0,0 +1,23 @@
+export interface Config {
+    llamaCppOrigin: string;
+    modelId: string;
+    databasePath: string;
+}
+
+export function readConfig(environment: NodeJS.ProcessEnv = process.env): Config {
+    const origin = environment.LLAMA_CPP_ORIGIN?.trim();
+    const modelId = environment.LLAMA_CPP_MODEL_ID?.trim();
+    if (!origin || !modelId) {
+        throw new Error("Set LLAMA_CPP_ORIGIN and LLAMA_CPP_MODEL_ID in .env (see .env.example).");
+    }
+    const url = new URL(origin);
+    if (!["http:", "https:"].includes(url.protocol) || url.username || url.password
+        || url.pathname !== "/" || url.search || url.hash) {
+        throw new Error("LLAMA_CPP_ORIGIN must be an HTTP(S) origin without credentials, path, query, or fragment.");
+    }
+    return {
+        llamaCppOrigin: url.origin,
+        modelId,
+        databasePath: environment.DATABASE_PATH?.trim() || "./data/token.sqlite",
+    };
+}